Field of the Invention
The invention relates to a stranded conductor containing a number of individual wires, wherein multiple individual wires that are embodied in an identical manner are arranged as outer wires around a central inner wire and wherein the individual wires form a composite that is encased by insulation. Furthermore, the invention relates to a method for producing a corresponding stranded conductor.
If multiple individual wires having a round cross section are arranged as outer wires around a central inner wire having a likewise round cross section so as to form a stranded conductor, when viewed in the cross section, wedge-shaped free spaces, herein under described as wedges, are thus formed on the circumferential side between the outer wires and a circular circumferential line. If an individual wire composite of this type is provided with an insulating synthetic material sheathing by way of example by an extrusion procedure, the wedges are thus also filled with the raw material of the synthetic material sheathing. Consequently, the weight of the synthetic material sheathing of a stranded conductor of this type depends upon the number and the size of each wedge on the circumferential side.
In some application fields, such as by way of example in the automobile industry, as light as possible a weight is desired or required for the stranded conductors that are used, which is why in these cases the aim is to achieve a cross section for the stranded conductor that is as close as possible to circular and accordingly contains as few as possible wedges that are also as small as possible. It is known for producing a stranded conductor of this type initially to arrange multiple individual wires having a round cross section around a central individual wire having a likewise round cross section and to subsequently compact this arrangement. Within the scope of this compacting procedure, the individual wires are deformed and the cross section of this individual wire composite takes on the form of an almost circular shape when a corresponding uniform pressure is exerted over the circumference. A compacted stranded wire of this type is by way of example disclosed in German patent DE 11 2010 004 176 T5 (corresponding to U.S. patent publication No. 2012/0217060) or also British patent GB 1 336 200 B.
As a consequence of this mechanical pressure treatment of the individual wire composite, the mechanical characteristics of the individual wires change so that an after-treatment, by way of example an annealing procedure, is required as an additional process step. In addition, the so-called fatigue strength under reverse bending stresses is reduced as a result of the compacting procedure.